| To accommodate the development of frequency standard techniques, frequency standards measurement and comparison techniques should have higher precision and resolution. A research into high precision frequency measurement is made on a series of new principles and new methods in the thesis.Both the analog and the digital scheme on the traditional difference frequency method are realized. The analog scheme is complex in circuits and narrow in measuring range, which can reach the frequency stability of 10-13/Ï„in time domain. The digital scheme uses phase relationship to process signal and is able to compare two signals with multiple relationships, which carry out in TTL and ECL circuits. A discussion about the digital scheme shows that the resolution of digital scheme in TTL circuits is 10 times lower than that of analog scheme, which are great impact of trigger error on measurement; the digital scheme in ECL circuits holds down trigger error in a great degree, which has higher resolution. At the same time, the existence of quantified error should not be neglected.To reduce quantified error, combining the length verier and the characteristic of signal transmission, a frequency measurement technique of digital phase processing on the time-space relationship is proposed in the thesis. Utilizing the regularity of phase difference between period signals, phase processing is made on comparison signals, which reduce effectively quantified error. Experiments validate the accuracy and the feasibility of the method. Moreover, the resolution of the method has the potential of improvement and it is a promising technique on precision frequency measurement. |
